<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body{
            background: radial-gradient(white,lightgrey);
        }
    #box{
        width: 500px;
        height: 500px;
        border: 8px solid red;
        border-radius: 50%;
        margin: 0 auto;
    }
    #clock{
        font-size: 80px;
        color: red;
        text-align: center;
        border: 8px solid red;
        width: 400px;
        height: 100px;
        margin: 200px auto;
    }
    </style>
    <script>
        window.onload=function(){
            var oBox=document.getElementById('box');
            var oClock=document.getElementById('clock');
            var timer=null;
            timer=setInterval(getTime,1000)
            function getTime (){
                var oDate=new Date();
                var Hour=oDate.getHours();
                var Minute=oDate.getMinutes();
                var Second=oDate.getSeconds();
                if(Hour<10){
                    Hour="0"+Hour;
                }
                if(Minute<10){
                    Minute="0"+Hour;
                }
                if(Second<10){
                    Second="0"+Second;
                }
                oClock.textContent=Hour+":"+Minute+":"+Second;
            }
            getTime();
        }
    </script>
</head>
<body>
    <div id="box"><p id="clock"></p></div>
</body>
</html>